style: rustfmt after the registry domain migration

The release gate failed cargo-fmt. The domain that replaced the IP-based
registry is longer, pushing several test assertions past the width limit, so
rustfmt wanted to re-wrap them. Pure line re-wrapping — no semantic change.

Caught by the pre-flight gate rather than after tagging, which is what it is
for.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/archipelago/src/api/rpc/package/set_config.rs

@@ -368,10 +368,7 @@ mod tests {
         let stack = vec!["archy-btcpay-db".to_string(), "archy-nbxplorer".to_string()];
         assert_eq!(select_backend_container("btcpay-server", &stack), None);
 
-        let with_backend = vec![
-            "archy-btcpay-db".to_string(),
-            "btcpay-server".to_string(),
-        ];
+        let with_backend = vec!["archy-btcpay-db".to_string(), "btcpay-server".to_string()];
         assert_eq!(
             select_backend_container("btcpay-server", &with_backend),
             Some("btcpay-server")
@@ -403,11 +400,15 @@ mod tests {
             Some("28.4")
         );
         assert_eq!(
-            image_tag("source.archipelago-foundation.org/lfg2025/bitcoin-knots:29.3.knots20260508").as_deref(),
+            image_tag("source.archipelago-foundation.org/lfg2025/bitcoin-knots:29.3.knots20260508")
+                .as_deref(),
             Some("29.3.knots20260508")
         );
         // No tag => None (don't mistake the registry port for a tag).
-        assert_eq!(image_tag("source.archipelago-foundation.org/lfg2025/bitcoin"), None);
+        assert_eq!(
+            image_tag("source.archipelago-foundation.org/lfg2025/bitcoin"),
+            None
+        );
         assert_eq!(
             image_tag("docker.io/library/redis:7"),
             Some("7".to_string())